The pair stepped out very low-profile at West Hollywood hotspot The Church Key restaurant for an intimate dinner.
Arriving at around 8 p.m., the pair "requested a private, curtained-off dining room for just the two of them," an onlooker tells PEOPLE, of the area that is typically reserved for large parties of 15 or more.
But the VIP treatment didn't go without gratitude.
"Khloé was sweet," the source says. "She told the manager that she loved everything."
Prior to their dinner date, the pair was most recently spotted taking in a Floyd Mayweather fight in Las Vegas last week.